Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability of extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as the travel from an outer suction port toward a center discharge port. The means for causing the orbiting of one of the scroll members is in many cases an electrical motor. The electric motor operates to drive the one scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
Scroll compressors depend upon a number of seals to be created to define the moving or successive chambers. One type of seal which must be created are the seals between opposed flank surfaces of the wraps. These flank seals are created adjacent to the outer suction port and travel radially inward along the flank surface due to the orbiting movement of one scroll with respect to the other scroll. Additionally sealing is required between the end plate of one scroll member and the tip of the wrap of the other scroll member. Because scroll compressors depend upon the seals between flank surfaces of the wraps and the seals between the end plates and opposing wrap tips, suction and discharge valves are generally not required.
While the prior art scroll machines are designed to run trouble free for the life of the scroll machine, it is still necessary to monitor the operation of the compressor and discontinue its operation when specific criteria have been exceeded. Typical operational characteristics which are monitored include the discharge temperature of the compressed refrigerant, the temperature of the motor windings, three-phase reverse rotational protection, three-phase missing phase/single phase protection and an anti-short cycle. The monitoring of these characteristics and the methods and devices for monitoring these characteristics have been the subject of numerous patents.
Recently, it has been found that by monitoring the vibrational characteristics of the scroll machine, it is possible to predict problems with a scroll machine before these problems result in a failure to the entire system. For instance, in a refrigeration or air conditioning system which incorporates numerous scroll machines, the abnormal vibration of one of the scroll machines can result in a fracture of the refrigeration tube associated with that individual scroll machine. The fracture of this tube will result in a total loss of the system refrigerant, possible damage to property, expensive repairs and in some cases could be hazardous. Accordingly, what is needed is a device which is capable of independently monitoring the vibrational characteristics of an individual scroll machine.
The present invention provides the art with a vibration sensing system which is incorporated into a more comprehensive compressor protection module which monitors all of the various operating characteristics of the compressor. The vibration sensing system will open the control circuit and stop compressor operation when the signal from a vibration sensor of the system exceed a preset limit for an accumulated time period.